Monday, 18 May 2009
Thinking outside the box again
The whole point with Dragonflying is that it should be simple and recapture some of the pioneer feel, so with that in mind I have been trying to assemble instrumentation for my Dragonfly without spending £200 plus on a Brauniger, Digifly (plus the speed probe at £70) or similar by thinking outside the box....thinking what pioneers would use.
They'd look to hang gliding, parachuting, camping, rock-climbing etc for equipment ideas...and after all, such areas of endeavour influenced Ben Ashman when he designed the Dragonfly: it doesn't have instruments, it uses lots of velcro for fixing, has a heavy duty carabiner for the back-up head gear, uses webbing straps, cycling pegs, rucksack snap-fasteners, etc.
So, yesterday I won an auction for a very small but practical altimeter, a Swiss made Thommen 15,000' with 3,000' on the first rotation, read easily, which is really all I would have needed, if there hadn't been inner scales. I am pretty sure from emailing the seller that it will adjust for QFE from QNH because after admitting that he didn't know how it works, he said:
"The only knob is the outer casing (which could be turned while wearing gloves). This rotates the front "glass" which has a red line on, and the outer dial that shows the 0, 500, 1000, 1500, 2000, 2500 measurements (the red line points to the zero) ... this provides a reference point to the inner black pointer of the guage which will alter based on height/pressure.
That sounds just the job, doesn't it! I got it for £36, which together with a second hand stopwatch and the hang gliding ASI means that I have most of what I need, with a saving of a couple of hundred pounds, which can be spent on my radio.
If anyone is aware of a Microavionics headset, Icom A20 or A22 and a good interface, please let me know. Canny cheapskate has a little money waiting.